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Fix no palette 8 bit surface gfxdraw segfault #3627

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Fix no palette 8 bit surface gfxdraw segfault #3627

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27 changes: 9 additions & 18 deletions src_c/SDL_gfx/SDL_gfxPrimitives.c
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Original file line number Diff line number Diff line change
Expand Up @@ -293,17 +293,13 @@ _putPixelAlpha(SDL_Surface *dst, Sint16 x, Sint16 y, Uint32 color, Uint8 alpha)
*((Uint8 *)dst->pixels + y * dst->pitch + x) = color;
}
else {
/* Patched on pygame-ce end to fix segfault when no palette
*/
Uint8 *pixel = (Uint8 *)dst->pixels + y * dst->pitch + x;
SDL_Palette *palette = format->palette;
SDL_Color *colors = palette->colors;
SDL_Color dColor = colors[*pixel];
SDL_Color sColor = colors[color];
Uint8 dR = dColor.r;
Uint8 dG = dColor.g;
Uint8 dB = dColor.b;
Uint8 sR = sColor.r;
Uint8 sG = sColor.g;
Uint8 sB = sColor.b;
Uint8 dR, dG, dB;
Uint8 sR, sG, sB;
SDL_GetRGB(*pixel, format, &dR, &dG, &dB);
SDL_GetRGB(color, format, &sR, &sG, &sB);

dR = dR + ((sR - dR) * alpha >> 8);
dG = dG + ((sG - dG) * alpha >> 8);
Expand Down Expand Up @@ -604,22 +600,17 @@ _filledRectAlpha(SDL_Surface *dst, Sint16 x1, Sint16 y1, Sint16 x2, Sint16 y2,
format = dst->format;
switch (GFX_FORMAT_BytesPerPixel(format)) {
case 1: { /* Assuming 8-bpp */
/* Patched on pygame-ce end to fix segfault when no palette */
Uint8 *row, *pixel;
Uint8 dR, dG, dB;
SDL_Palette *palette = format->palette;
SDL_Color *colors = palette->colors;
sR = colors[color].r;
sG = colors[color].g;
sB = colors[color].b;
SDL_GetRGB(color, format, &sR, &sG, &sB);

for (y = y1; y <= y2; y++) {
row = (Uint8 *)dst->pixels + y * dst->pitch;
for (x = x1; x <= x2; x++) {
pixel = row + x;

dR = colors[*pixel].r;
dG = colors[*pixel].g;
dB = colors[*pixel].b;
SDL_GetRGB(*pixel, format, &dR, &dG, &dB);

dR = dR + ((sR - dR) * alpha >> 8);
dG = dG + ((sG - dG) * alpha >> 8);
Expand Down
40 changes: 40 additions & 0 deletions test/gfxdraw_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -872,6 +872,46 @@ def test_bezier(self):
for posn in bg_test_points:
self.check_at(surf, posn, bg_adjusted)

def test_no_pal_8bit_surf(self):
"""
Test that gfxdraw methods do not segfault when passed with no palette
8 bit surface.
"""
s = pygame.Surface(
size=(512, 512), flags=0, depth=8, masks=(0xE0, 0x1C, 0x03, 0x00)
)

fg = (255, 255, 255)
points = [(10, 10), (100, 50), (50, 100)]
for name, args in (
("pixel", (s, 2, 2, fg)),
("hline", (s, 5, 50, 10, fg)),
("vline", (s, 10, 5, 50, fg)),
("line", (s, 0, 0, 100, 100, fg)),
("rectangle", (s, pygame.Rect(50, 50, 80, 40), fg)),
("box", (s, pygame.Rect(60, 60, 80, 40), fg)),
("circle", (s, 256, 256, 64, fg)),
("aacircle", (s, 256, 256, 64, fg)),
("filled_circle", (s, 256, 256, 32, fg)),
("ellipse", (s, 200, 200, 50, 30, fg)),
("aaellipse", (s, 200, 200, 50, 30, fg)),
("filled_ellipse", (s, 200, 200, 50, 30, fg)),
("arc", (s, 256, 256, 60, 0, 180, fg)),
("pie", (s, 300, 300, 60, 0, 270, fg)),
("trigon", (s, 100, 100, 150, 200, 50, 200, fg)),
("aatrigon", (s, 100, 100, 150, 200, 50, 200, fg)),
("filled_trigon", (s, 100, 100, 150, 200, 50, 200, fg)),
("polygon", (s, points, fg)),
("aapolygon", (s, points, fg)),
("filled_polygon", (s, points, fg)),
("textured_polygon", (s, points, s, 0, 0)), # use same surface as texture
):
try:
func = getattr(pygame.gfxdraw, name)
func(*args)
except Exception as e:
self.fail(f"gfxdraw.{name} raised an exception: {e}")


if __name__ == "__main__":
unittest.main()
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